Durable electrical switch

ABSTRACT

A manually operated switch having a sealed cylindrical housing is controlled through a pivotable, radially extending external actuator member and contains a pair of magnetically actuated sets of reed contacts for connection to the electrical circuit with which the switch is associated. A pair of permanent magnets are carried on resilient arms within the housing whereby each may be shifted into an operative position relative to one of the sets of reed contacts upon flexing of the associated arm. The external actuator member is disposed on an axle which extends into the housing through a circular seal and bearing to connect with a parallel internal actuator that bears against either of the resilient arms according to the direction of pivoting. This enables external actuator movement to be transmitted into the housing in the form of purely rotational motion through the circular seal thereby simplifying sealing problems and minimizing wear to provide a compact rugged and long lived mechanism.

United States Patent Scholl 1 July 4,1972

[72] inventor:

[52] U.S. [5i] int. Cl. [58] Field ofSearch...........................

..............335/205, 335/206 ..ll0lh 2l/80 .......33S/205, 206, 207

[56] 7 References Cited UNITED STATES PATENTS 3,l70,052 2/1965 Hajos..335I20S X 3,268,684 8/1966 Keller et al........ "335/206 UX PrimaryExaminerBernard A. Gilheany Assistant Examiner-R. N. Envall, Jr.Attorney-Charles M. Fryer et al.

[ ABSTRACT A manually operated switch having a sealed cylindricalhousing is controlled through a pivotable, radially extending externalactuator member and contains a pair of magnetically actuated sets ofreed contacts for connection to the electrical circuit with which theswitch is associated. A pair of permanent magnets are carried onresilient arms within the housing whereby each may be shifted into anoperative position relative to one of the sets of reed contacts uponflexing of the as sociated arm. The external actuator member is disposedon an axle which extends into the housing through a circular seal andbearing to connect with a parallel internal actuator that bears againsteither of the resilient arms according to the direction of pivoting.This enables external actuator movement to be transmitted into thehousing in the form of purely rotational motion through the circularseal thereby simplifying sealing problems and minimizing wear to providea compact rugged and long lived mechanism.

9 Claims, 5 Drawing Figures Patented July 4, 1972 3,675,169

3 Sheets-Sheet 1 INVENTOR ROLLAND D. SCHOLL Patented July 4, 1972 3Sheets-Sheet 2 INVENTOR ROL LAND D. SCHOLL a" g '5 ATZSRNEYS PatentedJuly 4, 1972 3 Shun-lint 3 INVENTOR ROLLAND D. SCHOLL 7" fizz- MATTORNEYS BACKGROUND OF THE INVENTION This invention relates toelectrical switches and more particularly to the switches of the formwhich are contained within a sealed housing and which have a movableactuator member extending externally thereof.

In certain specialized usages, electrical switches must combine ease ofoperation with a capability for an extremely high number of repeatedoperations without failure. One example of such a switch usage isdescribed in copending applicau'on Ser. No. l43,957 of Russell D. Pageet al. for Electro-I-Iydr'aulic Touch Control System filed May I7, 1971and assigned to the assignee of the present application. This copendingapplication describes a system which uses manually operated switches tocontrol electro-hydraulic motors which manipulate the earth moving bladeof a motor grader vehicle. In this context, the electrical switchesshould be capable of being operated repeatedly over a very long periodof time with high reliability while requiring a minimum of operatoreffort and diversion of attention. Moreover this must be achieved inadverse environmental conditions which may include extensive dust,vibration and exposure to sizable temperature variations and roughhandling.

Existing switch constructions do not fully realize these desirablecharacteristics in contexts such as that discumed above. Most of thevaried prior switch constructions were designed for operation in arelatively clean, stable and less abusive environment in indoor systemswhere the switch is either not subjected to extensive operations or elsemay readily be replaced by maintenance personnel without greatinconvenience.

The severe working conditions described above make it highly desirableto utilize switches of the form in which elements other than an externalactuator member are contained within a sealed housing. Preferably theexternal actuator is a pivoting element rather than a longitudinallysliding member, such as in a push button switch, since a pivotablesupport tends to be stronger and more durable under repeated use anddoes not actively assist the movement of dust, moisture or otherdamaging substances into the housing.

As heretofore constructed, switches of the form having a sealed housingwith a pivoting actuator member extending outside the housing have beencharacterized by an inherent sealing problem which detracts from theultimate durability of the switch over many cycles of operation. Inparticular the actuator member has been extended through an opening inthe housing and since it must pivot, the opening must be somewhat largerthan the actuator member itself. This in turn has required either aflexible diaphram type of seal or a sliding seal both of which haveundesirably limited life under repeated operation. Such seals tend todevelop imperfections after a period of use, which admit foreignsubstances into the housing. The problem has been aggravated as theforms of contacts heretofore used within the housing for performing theswitching function are prone to damage from foreign matter which isadmitted in this manner and have an undesirably limited life.

SUMMARY OF THE INVENTION The present invention provides a compact,sensitive electrical switch capable of sustained repeated operationunder adverse environmental conditions. The switch includes a'sealedhousing in which the pivotable actuator lever is wholly outside thehousing and motion of the lever is transmitted into the housing solelythrough the axle to which the lever is pivoted. This arrangementrequires only a circular rotary seal around the axle, such rotary sealshaving greater durability and reliability than sealing means which mustaccommodate to sliding motion. Within the housing, the switchingfunctions are performed by one or more sets of reed switch contacts eachof which is controlled by a magnet mounted on resilient means that maybe flexed by oscillation of the rotary axle. Thus no short lived sealingmeans nor wear prone mechanical mechanisms are necesary.

Accordingly, it is an object of this invention to provide a compact,reliable, rugged and readily operated electrical switch having a verylong life in terms of repeated operations and which retains thesequalities while subjected to severe external environmental conditions.

The invention together with further objects and advantages thereof willbest be understood by reference to the following description ofpreferred embodiments taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. I is a perspective view of a portion of the operator's seat of amotor grader vehicle or the like showing switches in accordance with theinvention mounted thereon for ease of control of powered elements of thevehicle;

FIG. 2 is a perspective view of one of the control switches of FIG. 1shown disassociated from the other structure thereof;

FIG. 3 is a section view of the switch assembly of FIG. 2 taken alongline 3-3 thereof;

FIG. 4 is a section view taken along line 4-4 of FIG. 3; and

FIG. 5 is a section view corresponding to FIG. 4 showing a modifiedinternal construction for the switch assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, a pairof switch assemblies ll and 12 are shown disclosed in a particularcontext which is exemplary of situations requiring electrical switchesof unusual durability and ruggedness combined with ease of operation. Inthis example the two switches 11 and 12 are secured together in coaxialrelationship and are disposed at the forward end of an armrest I3 of anoperator's seat 14 of a motor grader vehicle of the form described inthe above identified copending application Ser. No. 143,957 As describedin detail in the copending application, the two switches l l and 12 areused to control electro-hydraulic mechanism for selectively raising andlowering either side of the blade of the motor grader while an adjacentknob 15 operates a potentiometer to control the rate of blade movement.

In this working context, switches should require only light pressure andslight movement of operating buttons 16 to minimize operator effort anddiversion of attention from other control functions. Preferably, theswitches should have a configuration which enables the operators hand 17to rest comfortably on the arm rest 13 with the fingers extendingpartially around the switches ll and 12 so that each switch may beoperated by a slight easy movement of an individual finger. Theelectrical circuits controlled by the switches ll and 12 are not furtherdescribed herein inasmuch as the circuit mechanisms controlled therebyare described in detail in the above identified copending applicationand do not form a part of the present invention.

FIG. 2 shows a representative one of the switches [I removed from theother structure of FIG. I in order to better illustrate the switchconstruction. Switch 11 has a cylindrical housing 18 with an integrallyformed end wall 19 closing one end and a circular disc 21 secured to theopposite end to complete the enclosure.

One end wall of housing 18, end wall 19 in this instance, is providedwith a diametrically directed groove 22 in the exterior surface whichextends to a flat area 20 of the housing to receive a linear externalactuator lever 23 which supports control button 16 outward from the flatarea. Lever 23 is supported by an axle pin 24 extending into the housingalong the axis thereof as will hereinafier be described in more detail.Button 16 may be of essentially rectangular configuration with acylindrical outer surface having transverse small grooves 26 tofacilitate finger tip control and in this example is formed integrallywith the actuator lever 23. Actuator lever 23 has a bore at the endopposite button 16 into which the end of axle 24 is received and issecured to the axle in radial relationship thereto by a set screw 27.

While this particular example of the invention utilizes the button 16for fingertip control, it will be apparent that the switch may also bereadily operated by providing a lengthier lever 23 which lacks such abutton.

Groove 22 in the end wall of the housing is of slightly greater breadththan lever 23 to provide for a limited degree of pivoting movement ofthe lever. This provision of a groove 22 in the end wall 19 to receivelever 23 serves several useful purposes. The groove 22 defines highstrength durable stops for limiting pivoting movement of the actuatormember 23. ln addition, the disposition of the lever in the grooveenables two or more of the switch assemblies 11 to be disposed in acoaxial column with each such assembly adjacent to another but withoutcausing interference with motion of any of the externally situatedactuator levers 23. Further, the necessary electrical conductor wires 28may enter the housing 18 through an aperture 29 in the portion of groove22 remote from lever 23 also without interfering with the placement of aseries of such switches in proximity to each other. To provide forflexibility in the orientation of lever 23 and button 16, this exampleof the invention includes a second groove 22' in end wall 19 at rightangles to the first groove 22.

Accordingly, the external actuator lever 23 is situated wholly outsideof the housing 18 and motion of the actuator is transmitted into thehousing solely in the form of angular motion of the axle 24 about itsown axis. Considering now the mechanism through which angular motion ofaxle 2A is caused to operate switch contacts within the housing,reference should be made to FIGS. 3 and 4 in combination.

Referring initially to FIG. 3 in particular, end wall 19 of housing 18has a stepped tubular reentrant section 31 extending inward in coaxialrelation to axle 24 towards the opposite end wall defined by disc 21.Reentrant section 3] has a stepped bore including a first bore section32 adjacent external actuator lever 23 in which an annular seal 33 isdisposed. Seal 33 may be any of various forms of annular seal which prcvide for angular motion of a shaft encircled by the seal and in thepresent instance is a lip seal. Reentrant tubular section 31 of thehousing has a second bore section 34 of reduced diameter into which asleeve bearing 36 is disposed to journal axle 24 in housing section 31while minimizing friction and wear. Axle 24 extends a short distancethrough bearing 36 towards disc 21 and an inner actuator member 37 issecured thereto to extend radially from the axle in parallelrelationship to the external actuator lever 23. For purposes to bedescribed, a pin 40 extends from the free end of inner actuator lever 37in parallel relationship to axle 24.

Referring now to FIG. 4, a pair of encapsulated sets of reed switchcontacts 38 and 39 are disposed within housing 18 on opposite sides ofaxle 24 and inner actuator member 37. Each such reed switch 38 and 39may be of conventional construe tion and thus may have basic elementsconsisting of a closed tubular glass capsule 41 with a pair of flexiblereeds 42 and 43 of magnetizable material disposed therein in anarrangement wherein the reeds overlap for a short distance and eachconnects with a separate conductor wire 28 at opposite ends of thecapsule 41. As is understood within the art, reed switch contacts ofthis form may be opened or closed by appropriate movement of a permanentmagnet in the vicinity as the behavior of the two reeds is influenced bythe field of such a magnet. Several forms of reed switch, includingnormally open and normally closed forms, are available and each may beutilized in the context of the present invention. For purposes ofexample, the reed switches 38 and 39 shown in FIGS. 3 and 4 are of anormally open form in which the internal reeds 42 and 43 are slightlyseparated in the operlapping regions until such time as a magnet isbrought into close proximity to the capsule 41 at which time thecontacts close.

The switch capsules 4] are secured on an annular support 45 disposedadjacent end wall 19 and in coaxial relationship to re-entrant section31. As best seen in FIG. 3, the annular region occupied by support 45and capsules 41 is filled with a potting compound 50 to secure andprotect the reed switches.

First and second magnets 44 and 46 are secured at one end of angled leafsprings 47 and 48 respectively for selectively operating reed switches38 and 39 respectively. The opposite end of each spring 47 and 48 issecured to an associated one of a pair of circular springs 49 and 51respectively which are in turn secured to the inner wall of housing 18on opposite sides of the pin 40 which extends from the end of inneractuator lever 37. The two springs 49 and 51 exert opposite forces onpin 40 to establish a normal position for the pin and actuator levers 37and 23 at which the external lever 23 is centered in groove 22. At thisposition magnet support arms 47 and 48 abut opposite sides of housingreentrant section 31 and position the associated magnets 44 and 46adjacent reed switch capsules 38 and 39 respectively but at sufficientdistance therefrom that the reed switches remain inoperated until suchtime as the magnets are shifted from the normal rest position bymovement of pin 40.

Thus, in operation, springs 49 and 51 nonnally hold arms 47 and 48against reentrant section 31 thereby holding the magnets 44 and 46 outof operative relationship with respect to reed switches 38 and 39respectively and also holding the external operator's button 16 in thecentered position thereof. Upon movement of the operator's button 16 inone direction, such motion is transmitted by lever 23, axle 24, lever 37and pin 40 to distort spring 49 and thereby shifi arm 47 towards reedswitch 38. The resultant motion of magnet 44 into close proximity withthe reed switch 38 causes the contacts 42 and 43 thereof to close aspreviously described thereby closing a circuit between the twoassociated leads 28. Upon release of the button 16 spring 49 restoresthe above described elements to the original position withdrawing magnet44 from close proximity to reed switch 38 and opening the abovedescribed circuit. Motion of the operators button 16 in the oppositedirection distorts spring 51 to move magnet 46 toward reed switch 39 inan essentially similar manner thereby closing the circuit associatedwith that reed switch.

Variations may be made in the detailed mechanism for transmittingoscillatory movement of axle 24 into appropriate movement of the magnetsfor operating the reed switches. FIG. 5 illustrates one suchmodification. The general construction of the switch ll of FIG. 5 issimilar to that previously described except insofar as the magnets 44and 46' which operate reed switches 38' and 39' respectively areattached to arms 47' and 48' respectively which are in turn secured toopposite ends of a U-shaped leaf spring 51 to form extensions of theends thereof. The center of spring 51 is secured to the inner wall ofhousing 18' by a suitable screw 52 or the like and as in the previousinstance the spring normally abuts the two arms 47' and 48' againstopposite sides of reentrant section 31' of housing 18. The inneractuator lever 37' which extends radially from axle 24' is a triangularplate in this modification with a broad free end which spans the gapbetween arms 47' and 48 near the base of U-shaped spring 51. A pair ofspaced pins 53 extend from the free end of actuator lever 37' to contactarms 47' and 48' respectively whereby turning of axle 24 in eitherdirection causes one of the pins 53 to flex the adjacent leg of spring51 and thereby shifts the associated one of the magnets 44' or 46'towards the associated reed switch 38' or 39' to operate the reed switchas previously described.

Thus modifications of the invention are possible and it is not intendedto limit the invention except as defined in the following claims.

What is claimed is:

1. An electrical switch comprising:

a housing defining a chamber and having an aperture in one wall whichcommunicates with said chamber,

at least one set of reed switch contacts disposed in said housing andhaving electrical conductors extending therefrom to the exterior surfaceof said housing, said contacts being of the form which may be caused toopen and close by movement of a magnet in the vicinity thereof,

spring means disposed within said chamber of said housing and having afixed portion and a movable portion,

a magnet secured to said movable portion of said spring means formovement between a normal position and a second position to operate saidreed switch contacts,

an axle extending through said aperture of said housing, and

being movable angularly with respect thereto,

an inner actuator lever extending radially from said axle within saidchamber of said housing and having means bearing against said springmeans for flexing said spring upon angular movement of said axle toforce said magnet from said normal position to said second positionthereof, and

an external actuator lever extending radially from said axle outside ofsaid housing for turning said axle to operate said switch.

2. An electrical switch as defined in claim 1 further comprising anannular seal disposed in said aperture of said housing between said axleand the wall of said aperture.

3. An electrical switch as defined in claim 1 further com prising anannular bearing disposed in said aperture of said housing between saidaxle and the wall of said aperture.

4. An electrical switch as defined in claim 1 further comprising anannular bearing disposed between said axle and the wall of said apertureof said housing and an annular seal disposed in said aperture betweensaid axle and the wall of said aperture, said seal being outwardlydisposed in said aperture relative to said bearing.

5. An electrical switch as defined in claim I wherein said housing has agroove in an end wall thereof with said aperture in said housing beingcommunicated with said groove and wherein said external actuator leveris disposed in said groove and extends from an end thereof whereby aplurality of said switches may be disposed in end to end relationshipwithout causing interference with the movement of any of said externalactuator levers thereof.

6. An electrical switch as defined in claim 5 wherein said housing iscylindrical and said aperture extends along the axis thereof and whereinsaid groove and said external actuator lever extends substantiallyradially with respect thereto.

7. An elecuical switch as defined in claim I wherein said aperture isdefined by an annular reentrant section of said housing and wherein apair of said sets of reed switch contacts are disposed therein one oneach side of said reentrant section and wherein a pair of said magnetsare supported by said spring means, said magnets being disposed one oneach side of said reentrant section of said housing with each beingattached to said spring means by a separate one of a pair of arms whichnormally abut opposite sides of said reentrant section to define thenormal position of said magnets in said housing.

8. An electrical switch as defined in claim 7 wherein said spring meanscomprise a pair of circular springs each being secured to said housingand each having a separate one of said arms secured thereto.

9. An electrical switch as defined in claim 7 wherein said spring meanscomprises a leaf spring of U-shaped configuration having a base securedto the wall of said housing and having legs which extend towardsopposite sides of said reentrant section of said housing.

* l I l

1. An electrical switch comprising: a housing defining a chamber andhaving an aperture in one wall which communicates with said chamber, atleast one set of reed switch contacts disposed in said housing andhaving electrical conductors extending therefrom to the exterior surfaceof said housing, said contacts being of the form which may be caused toopen and close by movement of a magnet in the vicinity thereof, springmeans disposed within said chamber of said housing and having a fixedportion and a movable portion, a magnet secured to said movable portionof said spring means for movement between a normal position and a secondposition to operate said reed switch contacts, an axle extending throughsaid aperture of said housing, and being movable angularly with respectthereto, an inner actuator lever extending radially from said axlewithin said chamber of said housing and having means bearing againstsaid spring means for flexing said spring upon angular movement of saidaxle to force said magnet from said normal position to said secondposition thereof, and an external actuator lever extending radially fromsaid axle outside of said housing for turning said axle to operate saidswitch.
 2. An electrical switch as defined in claim 1 further comprisingan annular seal disposed in said aperture of said housing between saidaxle and the wall of said aperture.
 3. An electrical switch as definedin claim 1 further comprising an annular bearing disposed in saidaperture of said housing between said axle and the wall of saidaperture.
 4. An electrical switch as defined in claim 1 furthercomprising an annular bearing disposed between said axle and the wall ofsaid aperture of said housing and an annular seal disposed in saidaperture between said axle and the wall of said aperture, said sealbeing outwardly disposed in said aperture relative to said bearing. 5.An electrical switch as defined in claim 1 wherein said housing has agroove in an end wall thereof with said aperture in said housing beingcommunicated with said groove and wherein said external actuator leveris disposed in said groove and extends from an end thereof whereby aplurality of said switches may be disposed in end to end relationshIpwithout causing interference with the movement of any of said externalactuator levers thereof.
 6. An electrical switch as defined in claim 5wherein said housing is cylindrical and said aperture extends along theaxis thereof and wherein said groove and said external actuator leverextends substantially radially with respect thereto.
 7. An electricalswitch as defined in claim 1 wherein said aperture is defined by anannular reentrant section of said housing and wherein a pair of saidsets of reed switch contacts are disposed therein one on each side ofsaid reentrant section and wherein a pair of said magnets are supportedby said spring means, said magnets being disposed one on each side ofsaid reentrant section of said housing with each being attached to saidspring means by a separate one of a pair of arms which normally abutopposite sides of said reentrant section to define the normal positionof said magnets in said housing.
 8. An electrical switch as defined inclaim 7 wherein said spring means comprise a pair of circular springseach being secured to said housing and each having a separate one ofsaid arms secured thereto.
 9. An electrical switch as defined in claim 7wherein said spring means comprises a leaf spring of U-shapedconfiguration having a base secured to the wall of said housing andhaving legs which extend towards opposite sides of said reentrantsection of said housing.